Agricultural implement lift shaft helper spring assembly



April 28, 1953 M. H. PETERSON 2,636,334

AGRICULTURAL IMPLEMENT LIFT SHAFT HELPER SPRZIING ASSEMBLY Filed May 10, 1952 4 Sheets-Sheet 1 IN V EN TOR.

MERLE H. PETERSON. B

ATTORNEY.

April 28, 1953 M. H. PETERSON 2,636,334

AGRICULTURAL IMPLEMENT LIFT-SHAFT HELPER SPRING ASSEMBLY Filed May 10, 1952 4 Sheets-Sheet *2 INVENTOR.

MERLE H. PETERSON.

Y am, ,0. $94

A T TORNE Y.

April 28, 1953 M. HIPETERSON 2,536,334

AGRICULTURAL IMPLEMENT LIFT SHAFT HELPER SPRING ASSEMBLY Filed May 10, 1952 4'Sheets+Sheet 3 In INVENTOR. MERLE H. PETERSON.

am 1941M ATTORNEY.

April 28, 1953 M. H. PETERSON 2,636,334

AGRICULTURAL IMPLEMENT LIFT SHAFT HELPER SPRING ASSEMBLY Filed May 10, 1952 4 Sheets-Sheet 4 INVENTOR. MERLE H. PETERSON BY K d u flQw zbu ATTORNEY.

Patented Apr. 28, 1953 AGRICULTURAL IMPLEMENT LIFT SHAFT HELPER SPRING ASSEMBLY Merle H. Peterson, Grafton, Wis., assignor to Avco Manufacturing Corporation, Cincinnati, Ohio, a corporation of Delaware Application May 10, 1952, Serial No. 287,104

Claims.

This invention relates in general to farm equipment which uses a tool lift arrangement, and more specifically a helper-spring device suitable for use with farm equipment of this type.

In agricultural devices it is customary to raise and lower the working implement by rotation of a lift shaft to which the implement is connected through a system of linkages and bell crank arms. Hydraulic means or some other powerdriven type of device may be provided for rotation of the lift shaft or it may be rotated manually by an attached lever arm. Although not limited thereto, it is with manually operated agricultura1 implement lifting systems that this invention is primarily concerned.

It is a well-known expedient to use a tension spring connected between the manual lift lever arm and an anchor point on the implement frame for applying a force to the lift arm which is proportional to the length of spring extension. As the implement is lowered into operating position the tension spring extends more and more to supply an ever-growin force in support of the implement until finally the implement weight floats entirely on the tension spring. Obviously, as the implement is moved toward the operating position and the force supplied by the tension spring increases, the necessary manually applied force decreases.

During lifting operation the reverse is true and the amount of necessary manually applied force increases as the lift position is approached. True,

very little manual force is required to start theimplement toward its lift position; however, as the implement moves away from the operating position the tension spring contracts and supplies an ever-decreasing force in support of the implement. As a result, the necessary manually applied force must grow larger and larger as the implement is brought into lift position. It would be desirable to decrease the amount of this necessary manually applied force and at the same time allow the implement to float against the force of the tension spring when in the operating position.

Therefore it is an object of this invention to provide a helper spring assembly which acts during lift and lowering operations but which does not supply any portion of the float spring force during operation.

- It is a further object of this invention to provide a helper spring assembly for an implement lifting shaft which does not supply a lifting direction'force moment when the implement is in the operating position.

It is also a further object of this invention to provide a lift shaft helper spring assembly for a farm implement wherein the helper spring applies lifting force to the lift assembly only after the manual lift lever has been moved from its operating position toward its lift position.

Briefly considering a preferred embodiment of the invention, there is provided a ground supported farm implement carrying frame having a lift shaft mounted thereon for rocking movements between a rest position and a lift position. A system of linkages and bell crank arms connect the lift shaft to the working implement so as to raise and lower the implement as the lift shaft is rocked between its two maximum rotational positions. In addition, there is provided a novel helper spring assembly including a first toggle arm having one end attached to the lift shaft. Between the free end of the first toggle arm and a frame mounted pivot point there is connected a piloted spring which forms a second toggle arm. These two toggle arms are positioned relative to each other and relative to the rotational position of the lift shaft so that the toggle arms are in alignment only when the lift shaft is rotated slightly away from the rest position. In one preferred embodiment a com-- pression spring was used for the second toggle arm and the toggle arms when aligned assumed a relationship.

For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims, in connection with the accompanying drawings in which:

Fig. 1 shows a semi-mounted mower having a manual lift system including the novel helper mower frame II is supported by a single casterwheel l3 shown positioned transverse to the line of draft along which it rolls when the implement is being towed behind a prime mover such as a tractor. Retractable Wheel 14 is used only for parking and tractor attaching operations.

Housing l5 covers a belt drive system which is powered through telescoping drive shaft H to drive fly-wheel l8. Cutter shoe i9 is supported from frame H by push bar 26 and pull rod 23, portions of which have been deleted from the drawing in order to clearly show the remainder of the structure. Lever 22 along with the conventionally positioned elements shown connected thereto provide means for tilting cutter shoe l9 and cutter bar 23. Pitman rod is conventionally connected between cutter-bar Z3 and fly-wheel 88, through a part of the pitman rod has been deleted so that the remainder of the structure can be clearly shown.

Lift lever arm 3! alon with the lever arm brace 31 act in conjunction with lift shaft 32 and tension spring 33. to lift cutter-bar 23 through a system of bell-crank arms and linkages, best shown in Fig. 2. Lift arm latch 25 which is mounted so as to slide up and down lift arm 32) provides means for positioning lift arm relative to a lever sector plate 26 integrally attached to frame it. Latch lifting lever 27 along with the linking latch wire 28 is used to raise the lift arm latch along lift arm and out of engagement with sector plate 26 whenever it is desired to rotate the lift shaft between positions, i. e., rest and lift positions.

Implement lift link 34 is connected to arm 35 of bell crank 35. Tubular bearing sleeve 31 is integrally attached to bell crank 36, providing a bearing surface upon which the bell crank can rotate freely around lift shaft 32. At the free end of crank arm 38 an integrally attached U- shaped gag member 39 is provided to which one end of tension spring 33' is connected. Lever arm 30, which is attached to rotate lift shaft 32' is so positioned relative to gag member 39 as to strike stop bolt All as the lift shaft is rotated toward the lift position. After lift lever 30 strikes the gag member stop bolt 49, lever arm 30 and crank arm 38 move as a unit through the rcmainder of the lift cycle and the forces applied to lift shaft 32 by lift lever 30 and helper spring assembly 43, yet to be described, are transferred through bell crank 36 and lift link 33' to bring the implement into lift position. In other words, the weight of the implement acting on bellcrank 36 holds gag stop bolt against the forward edge of lift lever arm 36 during lift operations.

As thelift lever 30 is rotated back from lift position toward operating position, these same forces oppose the weight of the implement until tension spring 33 is extended suffieiently to apply a force to crank arm 38 which completely neutralizes the force applied to crank arm 35 by the implement, through link so. At this point bell crank 35 ceases to rotate with lift shaft 32. As lift lever 30 is moved farther back along sector plate 26 toward the stop bolt 4!, lift lever 30 ceasesto engage gag member stop bolt 40, thereby causing crank arm 38 and lift lever 36' to separate, as shown by the dotted line portion of Fig. 2, causing the weight of the implement to float against the force supplied to crank arm 38 by tension spring 33. Thus, lever 33 assumes a normal operating position against lever sector stop sleeve bearing 37 and transfer the weight of the implement to tension spring 33.

Now considering helper spring assembly 43 shown generally in Figs. 1 and 2, and more specifically in Figs. 3 and 4, it will be seen that bell crank 58 is keyed to lift shaft 32 and held in position thereon by means of a set screw 5|. A cam arm 52 is loosely mounted on lift shaft 32 between bell crank 58 and a tubular sleeve bearing 53 integrally attached to lift arm brace member 8|.

Cam arm 52 is held from rotational movements around lift shaft 32 by the action of stud 54 and set screws 57 and 58 mounted on the arms of bell crank Ell. As can be seen in Fig. 3 and Fig. 4, stud 54 extends through cam arm 52, between the two arms of bell crank 55 and through cam plate 55, and is threaded to receive a lock washer and nut 56 which, when tightened, secures cam arm 52 to bell crank 50. The longitudinal axis of cam arm 52 is positioned relative to the arms of bell crank by means of set screws 5'! and 58. For example, assuming the lock washer and nut 56 to be loose, a loosening of setscrew 58 and; a tightening of set screw 5'? moves the longitudinal axis of cams arm 52 closer to alignment with the lower arm: of bell crank 53. On the other hand, when set screw 5'5 is loosened and set. screw 58tigh-tened the longitudinal axis. of cam arm 5% moves closer to alignment with the other arm of bell. crank 58. Thus, since bell crank 58] is keyed to lift shaft 32, adjustment of set screws 51' and lit actually shifts the rotational position of cam arm 52 around lift shaft 32, and; the. lock-washer nut of combination provides means. for-holding cam arm 5?: in the adjusted position.

The free end of cam arm 5:2 is. integrally attached to, an a-rcuate shaped member 59.: which provides a cam surface against which, as will be. seen, the roller portion of the spring, toggle arm bears. Thus. it can. be said that cam arm. 52', along with bell crank 50, stud 5d, cam. plate 55, and nut 58 form what can be called. a first togglev arm.

The second togglearm is formed by a guided compression spring assembly which applies av force between, pivot bearing plate 63 and acamroller' 6! which bears against the concave face of cam. 5.9. Compression. spring 62 is. guided by a telescoping arrangement comprising an outer tubular sleeve 63 and. a sliding, inner tubular sleeve 64. The inner tubular sleeve as is. threaded at its pivot end to receive spring compression adjusting nut 65 which. acts as an adjustable stop for washer 5E.

Theouter tubular sleeve. 63 is integrally at, tached to one sideof a circular. flange. member 61- and roller. 5!- is mounted for rotation between two cars 58 which are integrally attached to the otherside of the same circular flange member; Guide rod (it is also; integrally attached to air-- cular flange member 6 t to form a. central axisfor the: complete spring guide assembly. The other end of, guide rod 69 is threaded. to receive a: stop nut to... Compression. spring 62; slides over tubular sleeve 83 and is held between washer lit and circular flange 87. An arcuate'shaped, pivot plate ii is mounted. to slide on guide rod. Sabetween. the threaded end of the inner tubular sleeve 6 and the pivot. bearing plate Pivot bearing plate Bil is rigidly attached to frame it by side anchor plates 12.

The position of cam arm 52 relative, to; lift shaft 32. is critically When lift arm 30 rests against the lower lever sector stop bolt: 48 the implement is invoperating position and cam. arm,

52 should be fixed on liftsha-ft- 32; so: that roller.

BI is in its lowest position o'n the concave sur bisecting the angle between the arms of bell crank 59 so that set screws and 58 have approximately equal up and down adjustmenttravel at this critical point.

The action of the cam-faced first toggle arm and the guided compression spring second toggle arm, after they are once correctly positioned, depends upon the rotational position of lift shaft 32. As has been stated, when the implement is in operating position lift lever 39 rests against lever sector stop bolt 4|, and cam roller Bl is in its lowest position on the concave surface of cam 59. It will be noted that in this position the force applied by compression spring fiz tends to rotate lift shaft 32 toward the operating position, i. e., drive lever arm against lever sector stop bolt iii. In other words, the force supplied by compression spring 62 has a component which tends to drive lever cam 52 in a clockwise direction looking at the cam from the side shown in Fig. 4.

As lift lever arm 30 is moved toward the lift position, thereby rotating lift shaft 32 in a counterclockwise direction, cam arm 52 and cam 59 move from the solid line position shown in Fig. 4

toward the dotted line position. As lever arm 39 approaches contact with gag stop bolt 50, roller 6| moves up the concave face of cam 59 until the toggle arms are in alignment and compression spring 62 applies its full force through cam arm 52, transversely to the axis of lift shaft 32. When lever arm strikes gag stop bolt 49, roller 6! reaches its uppermost position on the surface of cam 59 and exerts a component of force through cam arm 52 tending to rotate lift shaft 32 toward the lift position. It can now be seen, durin the remainder of the lift operation, that the force of compression spring 62 is applied through lift shaft 32 to carry a portion of the implements weight.

When it is desired to lower the implement from the lift to the operating position, the latch lifting lever 21 is actuated to move lift arm latch 25 up along lift arm 35 and out of engagement with lever sector plate 26. The weight of the implement then acting through implement lift link 34 and bell crank 33 tends to rotate lift shaft 32 in a clockwise direction when viewed from the side shown in Fig. l. At this position guided compression spring 62 and tension spring 33 both exert a force on lift shaft 32 which oppose the weight of the implement, requiring only a small additional manually applied force against the free end of lever arm 39. As lift shaft 32 is rotated farther toward the operating position, tension spring 33 extends and accepts an ever-growing portion of the implements weight.

When the force applied by tension spring 33 through bell crank 36 exactly neutralizes the weight of the implement applied to crank arm 35 through lift link 34, bell crank 36 ceases to rotate with lift shaft 32 and as lift shaft 32 continues to rotate toward the operating position, lift lever arm 30 breaks out of engagement with gag stop bolt 40 and moves back toward stop bolt 4!, as shown by the dotted line portion of Fig. 2. The weight of the implement then floats against the force applied by tension spring 33. At this point cam face 59 has rotated to a position similar to that shown by the dotted lines in Fig. 4, and as lift shaft 30 moves still farther toward lever sec- 6 tor stop bolt 4 I, roller 6| starts moving downward over the face of cam 59 in toggle action, coming to rest at the lowermost portion of the cam face just beforelift lever 30 strikes stop bolt 4 I. When roller BI is in this position the force of compression spring 52' is applied to--hold lever arm 30 against lever sector stop bolt ll out of engagement with gag stop bolt 40.

It-can now be seen that helper spring assembly 43 actually comprises two toggle arms with cam arm 52 bell crank 59, stud 54, cam plate 55 and nut 56 forming an assembly making up the first toggle arm. Guided compression spring 62 held between roller BI and pivot anchor plate to forms the second toggle arm.

It now also can be seen that helper spring assembly 43 is only effective to help neutralize the weight of the implement during lift operation periods and does not supply a lifting direction forcemoment when the implement is in the operating position. It can be seen further that the helper spring assembly 43 applies a lift force to aid in lifting the implement only after manual lift lever 39 has been moved from its operating position toward its lift position.

While the compression spring type helper spring assembly which has been shown and described is at present considered th preferred embodiment of the invention, it will be obvious to those skilled in the art that variou changes and modifications may be made therein without departing from the scope of the appended claims.

Having thus described my invention, I claim:

1. In a farm tool the combination comprising a ground supported frame, a lift shaft supported on said frame for rocking movements between a rest position and a lift position, a lever arm for rocking said shaft between the rest and lift positions, a helper spring assembly comprising a first toggle arm having one end connected to said shaft, a piloted spring compressed between the other end of said first toggle arm and a frame mounted pivot point forming a second toggle arm, said toggle arms being in alignment only when said lift shaft is rocked to a position slightly away from the rest position.

2. In a farm tool the combination comprising a ground supported frame, a lift shaft supported on said frame for rocking movements between a rest position and a lift position, a lever arm for rocking said shaft between the rest and lift positions, a helper spring assembly comprising a first toggle arm having one'end connected to said shaft, a second toggle arm comprising a piloted spring connected between the other end of said first toggle arm and a frame mounted pivot point for applying force against said first toggle arm, said toggle arms being aligned only when said lift shaft is rocked to a position slightly away from the rest position.

3. In a farm tool the combination comprising a ground supported frame, a lift shaft supported on said frame for rocking movements between an operating position and a lift position, a lever arm for rocking said shaft between the operating and lift positions, a helper spring assembly comprising a first toggle arm having one end formed to provide a cam surface and the other end connected to said shaft, a second toggle arm comprising a piloted spring compressed between a frame mounted pivot point and a cam roller which bears against the said cam surface, said toggle arms being in 180 alignment only when said lift shaft is rocked slightly away from the operating position.

4 In a. fiarm tool; the: combination, compri g an: implement flame; snpportsd. by' round en asw ns; a. frame mounte mp i i shaft for rotation. between an implement operat? ing position and. an implement,- lifit. position; a toggle arm having. one and. connected to said his; Sim-11,211, second toggle armv com-prisin a: gu d m compression spring helchoatwefin:aframe:m um e61 pivot and the; other emioi. said. fir toggle. arm the longitudinal oi anmsi lying in a common plane, transxzersa to. the: 055 said. lift shafit when, a1-ignment, said to learms being in lino when said 11111;: sham turned sfighmg from operating, pasitiom, whereby,- said compression spring applissai-ome-to-aid in: rotating saidl-i-it- Shaft into lift; position from. a ositiom where the; toggle arms; are.- in alignment. andalso a fierce tendin to hold said: iitt shait, from being; minted; from the operafing, position. to, tha position whae said toggle arms are, in alignment 5. In a; farm tool tho combination. comprising.

a ground supported frame, a lift; shaft, supported.

on sam-v frame. for ranking movement between. am

8: operating: position and, a; lift position a float spring, having. twonmdsrv one,- of said float spring ends being anchorest to, said; irame, a farm. impiement a bell; crank. mountedtorotate around. saidiliit shaft having; a first arm linked-to; said farm implement and a, second arm supporting a L-i-shapedI gag. member and connected tothe,- free end of said float. spring, a, lever, arm for mokmgysaid lii-tlshafitbetweem the operating and lift, positions; mounted. on saidlift shaft for engaging g; said; U shaped, gag memben a.- helper spring assembly comprising". a first toggle arm having onoend. formed, torprovide a cam surface and.: the, other. end connectedz tQxSaid: shat-1;,- a, see- I and tegglearm comprising a pilotedspring compnessedbetween: a frame; mounted pivot. point; and; a, camroll'erwhich bears: against; the: camsurfasa of. said first toggle arm said; first and seeonditeg-gle armsheing inalignmentonly when; said lifisf shatt. is; rocked; slightly away from the operating; Desition;

MERLE PETERSON No. references. citbdl 

